Although the useful lifetime of cut flowers can be extended by refrigeration and by use of certain chemical preservatives, the fact that many flower varieties are shipped as cut flowers over long distances has provided strong motivation to develop improved methods for extending flower bloom life. Placing cut flowers in water affords some measure of preservation by keeping the flowers hydrated, but chemical preservatives are often added to water solutions to extend bloom life further.
Among the chemical preservatives currently in use are carbohydrates such as sucrose, glucose, and fructose; acidifying agents for producing a solution pH of 3 to 7; and agents for preventing stem blockage (Nowak et al., 1990, page 44 et seq.). A number of preservative compositions which contain various mixtures of the above are commercially available, including Chrysal.TM. and Floralife.TM., for example.
Other chemical preservatives currently in use include agents which appear to interfere with the action of ethylene, which plays an important role in senescence. Such preservatives include silver thiosulfate (STS), 2,5-norbornadiene, aminooxyacetic acid (AOA), and aminoethyoxyvinylglycine (AVG). Silver thiosulfate and 2,5-norbornadiene act by antagonistically blocking ethylene action. Aminooxyacetic acid and aminoethyoxyvinylglycine, on the other hand, act by inhibiting ethylene synthesis. Although these agents have been shown to be effective floral preservatives (Reid et al., 1991; Beyer, 1976; Sisler, 1983; Fujino et al., 1981; Baker et al., 1977) and are sometimes effective when used in combination with other chemical preservatives such as mentioned above, their toxicity and expense present significant drawbacks. Accordingly, new post-harvest floral preservatives that are non-toxic and environmentally safe have been sought.
Isoniazid has long been employed as a first-line drug in anti-tuberculosis therapy; however, use of isoniazid for increasing the longevity of cut flowers has not been known.